With reference to FIG. 1, a motion transmission system in a bicycle 1000 comprises a chain 100 extending between toothed wheels 1002, 1004 associated with the axle of the pedal cranks 1006 and with the hub 1008 of the rear wheel 1010. When—as in the case shown—at at least one of the axle of the pedal cranks 1006 and the hub 1008 of the rear wheel 1010 there is an assembly of toothed wheels 1002, 1004 comprising more than one toothed wheel 1002, 1004, and the motion transmission system is therefore provided with a gearshift 1012, a front derailleur 1014 and/or a rear derailleur 1016 are provided for.
Hereinbelow in the present description and in the attached claims, the toothed wheels 1002 associated with the axle of the pedal cranks 1006 are also called chainrings, and the toothed wheels 1004 associated with the hub 1008 of the rear wheel 1010 are also called sprockets.
In case of an electronic gearshift, each derailleur 1014, 1016 comprises a guide element 1018, 1020,—also known as chain guide or, in case of a rear derailleur, rocker arm—movable to displace the chain 100 among the toothed wheels 1002, 1004 in order to change the gear ratio, and an electromechanical actuator to move the chain guide 1018, 1020.
Each electromechanical actuator in turn typically comprises a motor, typically a suitably powered electric motor, coupled with the chain guide 1018, 1020 through a linkage such as an articulated parallelogram, a rack system or a worm screw system. However, in principle the chain guide 1018, 1020 could also be directly connected to the electric motor.
Typically, the electric motor is provided with a gear reduction mechanism. The assembly of electric motor and gear reduction mechanism is referred to hereinafter as geared motor. The actuator typically further comprises a sensor or transducer of the position, speed, acceleration and/or direction of rotation, of the rotor of the motor or of any movable part downstream of the rotor, down to the chain guide 1018, 1020 itself. It is worthwhile emphasizing that slightly different terminology from that used in this context is also in use.
Control electronics changes the gear ratio automatically, for example based on one or more detected variables such as the travel speed, the cadence of rotation of the pedal cranks, the torque applied to the pedal cranks, the slope of the travel terrain, the heart rate of the cyclist and similar, and/or the gear ratio is changed based on commands manually input by the cyclist through suitable control members, for example levers and/or buttons, typically provided on one or two manual control devices 1022 mounted on the handlebars 1024 of the bicycle 1000.
Typically, the derailleur 1014, 1016 includes a support body 1026, 1028 that is configured to be attached to the frame of the bicycle 1000, and the chain guide 1018, 1020 connected to the support body 1026, 1028 by means of two connecting rods or arms, the ends of which are pivoted to the support body 1026, 1028 and to the chain guide 1018, 1020 to form the aforementioned articulated parallelogram.
The geared motor drives the articulated parallelogram open and closed and as a consequence the displacement of the chain guide 1018, 1020 among the toothed wheels 1002, 1004.
As an alternative or in addition to an electronic gearshift, modern bicycles are often provided with electric, electronic and electromechanical apparatuses, including suspensions, lighting systems, sensors of the travel speed, of the cadence of rotation of the pedal cranks, of the torque applied to the pedal cranks, of the slope of the travel terrain, of the heart rate of the cyclist and similar, satellite navigation systems, training devices, anti-theft systems, cycle computers capable of providing information about the status of the bicycle, of the cyclist and/or of the route, etc.
All of the aforementioned electric, electronic and electromechanical apparatuses consume electrical energy, supplied by one or more battery power supply units, possibly rechargeable. Although it is possible to exploit, for recharge, the movement of the bicycle itself through a dynamo, it is nevertheless important to save as much energy as possible. The aforementioned apparatuses are therefore in general provided not only with a proper on/off switch, but also with a standby mode.
Under wait or standby or sleep or low consumption mode, a condition in which an electric, electronic or electromechanical device is not operating, but is ready to switch from a temporary inactivity state to an operating mode is meant to be indicated; in standby mode, only those circuits that allow the device to start upon receiving commands that involve the actuation thereof are typically kept operating, thus there is a low consumption of electrical energy.
Vice-versa, in an operating mode, an electric, electronic or electromechanical device is ready to receive commands or in general inputs and to carry out tasks, even though it can be engaged only in waiting for commands and inputs, without carrying out any specific task.
The switching from a standby mode to an operating mode is indicated herein as wake of a device. More in general, under wake of a device it is meant to encompass maintaining a device in an operating mode, preventing it from entering a standby mode. A same signal or a similar signal can be used in both cases.
For bicycle apparatuses that can be reached by the cyclist, such as for example the manual control devices associated with the handgrips of the handlebars or cycle computers fixed to the handlebars or in the front part of the frame, the wake signal is easily associated with the pressing of a button or with the actuation of a lever by the cyclist.
For apparatuses arranged in parts of the bicycle remote from the hands of the cyclist, such as for example the derailleurs, brakes and suspensions, the wake signal can be a signal, specific or not, received from another on-board apparatus, for example one of the just mentioned ones. Thus, for example, the actuation of an upward gearshifting request lever by the cyclist can be used to generate a wake signal of the electronics of the manual control device of which the lever is part and/or of an electronic derailleur to which the signal is intended and is transmitted.
However, in case of apparatuses connected in a wireless network, there exists the problem that at least the wireless communication device of an apparatus must be in operating mode in order to be able to receive a signal from another apparatus. Therefore, it is not possible to exploit a remote signal as a wake signal.
In such an operating mode, the wireless communication device has a high consumption of electrical energy, and therefore it is desirable that such a mode is limited to when the bicycle is in use.
In particular, the wireless electronic derailleurs are provided with a wireless—for example radio or infrared—communication device that receives the gearshifting request signals from the manual control devices fixed to the handgrips of the handlebars and/or from a control unit that receives them from such manual control devices or that processes them automatically.
When the bicycle is in use, the wireless communication devices of the electronic derailleurs must therefore be always in operating mode in order to be ready to receive such gearshifting request signals at any moment. Only when the bicycle is stopped for a prolonged period, the wireless communication devices of the electronic derailleurs can enter standby mode.
It is therefore necessary for the wireless electronic derailleur to be itself equipped with a detector of the movement of the bicycle, so that the signal emitted therefrom can be used as a wake signal.
In order to distinguish a prolonged stop, for example in a parking slot or a garage, from a temporary stop, for example at a traffic light, it is possible to use a timer and/or to use the same signal emitted by the movement detector to prevent the standby mode to be entered, namely as an anti-sleep signal.
It should be understood that the other devices of the wireless electronic derailleurs, for example the controllers of the motors, can instead enter standby mode also during the use of the bicycle and be woken by a wake signal generated by the wireless communication devices when they receive the gearshifting request signals.
US2001/048211 A1 discloses a bicycle gearshift comprising a sensor of the rotation of a crank arm or of a pulley of a rear derailleur, said rotation being interpreted as a movement of the motion transmission chain from the crank arms to the rear wheel. In the case of the crank arm, the sensor is of a potentiometric type. In the case of the rear derailleur, the sensor comprises a C-shaped magnetic element fixed to the pulley and at least one Hall-effect sensor or a Reed relay mounted on a half-cage supporting the pulleys of the chain-tensioner of the rear derailleur.
U.S. Pat. No. 8,909,424 B2, on which the preamble of claim 1 is based, discloses a bicycle wireless electronic derailleur, comprising a control unit which includes a wireless receiver that receives shift request signals from a wireless transmitter, wherein the control unit includes a CPU and a wake sensor operatively associated to the CPU. The derailleur includes a base part attachable to the bicycle, a movable part, a chain guide attached to the movable part and a linkage that interconnects the base part to the movable part to enable the movable part to move relative to the base part by means of a motor; the control unit with the wake sensor is housed within the movable part. The wake sensor is of a vibrational type, but the document generically discloses that magnetic reed switches configured to detect magnets attached to moving elements of the bicycle might be used.